This might be a specific problem that may or may not belong on this forum but since there is an apple device section I figured I'd try.

I have a JVC DLA X750R pj. I am running an Apple TV 4k through my Yamaha RX A3050 receiver. My specific projector model has a known issue. After calibrating specific user settings for things like Blue Ray or HDR the pj will auto default the gamma to setting "D" which cannot be calibrated well. Every time you pause a movie or switch sources it changes the picture settings in the gamma mode. SOOOO HD Fury vertex is the fix for this problem. Vertex will trick the pj to holding the last used picture setting for certain signals that you program in. Works great with my cable system and my Blue Ray Player. If I put in an HDR dvd the vertex tells the pj to switch to my HDR user settings and holds it until that signal is changed to SDR etc....

HOWEVER, my Apple TV seems very confused by the vertex. my Apple will no longer allow me to enable HDR. prior to the vertex HDR enabled fine and I could rent HDR movies using my pj HDR calibrated settings (of course it would default the gamma to D all the time). Now my Apple TV says the device I am sending the HDR signal to does not accept HDR and it reverts itself to SDR. I cannot get past it. Any thoughts on this?

It all matters.....just not very much.